"When I left the Marines, I never thought I would find as committed, as professional, as patriotic a group of individuals", the retired four-star general wrote.
Firing Sessions or special counsel Robert Mueller - a move that has reportedly been considered by Trump and that would effectively end the Russian Federation probe that has been vexing him - could be one step too far even for this president.
"He is a Great American. and a Great Leader".
When Trump took office, he named Kelly as Homeland Security secretary.
Priebus said the president wanted go "a different direction" and that it was "a healthy thing".
She warned against his appointment, saying "no Washington insider, regardless of who it is, should serve as President Trump's chief of staff". By ordinary standards, Spicer and Priebus have been far too loyal to Trump for far too long - to their own detriment.
"When you see these thugs being thrown into the back of a paddy wagon - you just see them thrown in, rough - I said, 'please don't be too nice, '"Trump said".
White House Press Secretary Sarah Sanders told the press that talks of Priebus' departure started two weeks ago, and that it had nothing to do with Scaramucci.
That same day, the feud escalated when The New Yorker revealed Scaramucci had in a phone interview attacked Priebus in harsh and even vile terms, calling him a "paranoid schizophrenic" and using a vulgar term to illustrate Priebus's attempts to block him from a White House post. "He has been a true star of my Administration", Trump tweeted. Then, on Thursday, he was the subject of a remarkable and profane public rebuke by Trump's newly appointed White House communications director, Anthony Scaramucci.
Trump broke the news in the only way we've come to expect from him: on Twitter. Trump had focused on him in recent days, telling those close to him that he believed military discipline was what his administration needed. Former White House Press Secretary Sean Spicer also departed earlier this week. "Incredible", Trump said to applause.
Scaramucci has openly accused Priebus of leaking inside information to the press and threatened to contact the Federal Bureau of Investigation and the Department of Justice to shore up the leaks.
Priebus says he supports the president and that he's "doing great" personally. House Homeland Security Committee Ranking Member Bennie Thompson (D-Mississippi), told CBS News the president's decision was "rushed".
"He knows how to do this: with common sense and good leadership", said Kelly's longtime friend, who spoke on the condition of anonymity to offer frank opinions.